The phrase "200 units of semaglutide" is primarily associated with compounded versions of the medication, where a vial's contents are measured in units for administration using an insulin syringe. Branded products, such as Ozempic and Wegovy, are supplied in pre-filled, multi-dose pens with dosage marked in milligrams (mg), not units. This distinction is critical for understanding the lifespan of your medication, as the answer depends on the formulation and prescribed weekly dose.
Understanding Semaglutide Units: Compounded vs. Branded
The way semaglutide is measured differs between compounded pharmacies and brand-name manufacturers. Compounded semaglutide is a version of the drug that is custom-made by a pharmacy, but it is not FDA-approved and may not have the same rigorous testing as branded products.
- Compounded Semaglutide (Measured in Units): These formulations often come in vials, and dosages are drawn out with a syringe. A typical compounded vial might contain 5 mg of semaglutide, equating to 200 units if the concentration is 0.025 mg per unit. This means the total available dosage in a 200-unit vial is 5 mg.
- Branded Semaglutide (Measured in Milligrams): Medications like Ozempic and Wegovy are FDA-approved and come in pre-filled pens. These pens deliver fixed weekly doses measured in milligrams (e.g., 0.5 mg, 1 mg, 2 mg). Patients select their prescribed dose using a dial on the pen. The pens themselves are designed to be used for a fixed period (typically 4-8 weeks) once opened.
The Lifespan of a 200-Unit (5mg) Compounded Semaglutide Vial
Assuming a 200-unit vial contains a total of 5 mg of semaglutide, its duration depends entirely on the patient's weekly dosage. However, a major limiting factor is the medication's stability after the vial is first punctured. The manufacturer or compounding pharmacy's guidelines must be followed, but a common standard is a 28-day (4-week) use-by period after opening, even if stored properly in the refrigerator.
Here is a breakdown of how long a 5 mg (200 unit) compounded vial could theoretically last based on dosage, before considering the 28-day rule:
- 0.5 mg weekly dose: The 5 mg vial would contain 10 weekly doses (5 mg / 0.5 mg = 10 weeks). However, because the vial must be discarded after 28 days (4 weeks), you can only use 4 of these doses from a single vial, and the rest must be thrown away.
- 1.0 mg weekly dose: The 5 mg vial contains 5 weekly doses (5 mg / 1.0 mg = 5 weeks). This would last for the full 5 weeks, as it falls within the 28-day stability period.
- 2.0 mg weekly dose: The 5 mg vial contains 2.5 weekly doses. You would use two doses and part of a third before needing a new vial.
Duration of Branded Semaglutide Pens
Unlike compounded versions, branded Ozempic pens have a consistent lifespan once opened, based on their stability rather than the number of units. The manufacturer states that once a pen has been used for the first time, it should be used for 56 days (8 weeks) at most, regardless of whether it is refrigerated or stored at room temperature (under 86°F/30°C).
Branded Semaglutide Pens: Doses and Lifespan
- Ozempic: For maintenance doses of 0.5 mg, 1 mg, or 2 mg, a single pen holds four weekly doses and lasts for one month.
- Wegovy: Approved for weight management and available in higher maximum doses (up to 2.4 mg weekly), Wegovy pens are also single-use pens containing a set number of doses.
The Pharmacokinetics of Semaglutide
Beyond the physical quantity and shelf life, the drug's half-life dictates its duration in the body. Semaglutide has an impressive half-life of approximately one week. This pharmacokinetic property allows for its convenient once-weekly dosing schedule. The long half-life is due to its binding to albumin in the bloodstream, which protects it from rapid breakdown and elimination.
How Semaglutide Clears the Body
- Steady State: After several weekly doses, the concentration of semaglutide in the body builds up to a steady state, typically taking 4 to 5 weeks.
- Elimination: After the last dose, it takes about 5 weeks for the semaglutide to be almost completely eliminated from the body. This is why, if you miss a dose, you can often take it within a few days without significantly impacting your treatment plan.
- Effect Diminishment: The therapeutic effects, such as appetite suppression and blood sugar control, gradually diminish over several weeks after discontinuing treatment.
Comparison Table: Compounded vs. Branded Semaglutide
| Feature | Compounded Semaglutide (often in units) | Branded Semaglutide (e.g., Ozempic, Wegovy) |
|---|---|---|
| Dosing Unit | Units (e.g., 200 units = 5 mg) | Milligrams (e.g., 0.5 mg, 1 mg, 2 mg) |
| Formulation | Vials, requiring a separate syringe | Pre-filled, multi-dose pens |
| Open Shelf Life | 28 days once opened (refrigerated) | 56 days once opened (refrigerated or room temp) |
| Regulatory Status | Not FDA-approved | FDA-approved |
| Duration (200 units/5 mg) | Variable based on dose, limited by 28-day shelf life. | Not applicable. Dosing is based on mg per pen, typically lasting 1 month (4 doses) |
Conclusion
For those asking how long 200 units of semaglutide last, the answer is complex and dependent on the medication source. A 200-unit compounded vial contains 5 mg of medication, and its practical lifespan is limited by a 28-day stability period once opened, meaning the number of weekly doses you get will be constrained. For branded Ozempic and Wegovy, which use milligrams, the duration is defined by the fixed doses per pen, with a 56-day use-by date after first use. Ultimately, the duration depends on your individual dosage, and it's essential to follow the specific instructions from your healthcare provider and pharmacy. An Ozempic pen contains four weekly doses and lasts one month, but the half-life means its effects linger in the body for about five weeks after the last injection. Always consult with a healthcare professional to ensure safe and effective use of this medication. More information on semaglutide's clinical pharmacology can be found through resources like the National Institutes of Health.
